This application claims a priority based on German application 199 36 644.6, filed Aug. 4, 1999, and the contents of that application are incorporated herein by reference.
This invention relates to electric air-pump apparatus for motor vehicles of a type having a mounting plate to which a housing of an electric motor and a pumping device are to be attached, and having a sound absorber formed by the mounting plate and a sound-absorber cap attached thereto.
German patent document (DE 41 09 548 C2) discloses an electric air-pump apparatus of this type. This known electric air-pump apparatus has a sound-absorber cap that surrounds an electric motor, with an annular sound absorbing space thereof surrounding the electric motor. A pumping device thereof is a vane-type pumping device in which the mounting plate forms a base plate of a pump chamber.
There are disadvantages to this known electric air-pump apparatus. By positioning the sound absorber around the electric motor, an outer diameter of this electric air-pump apparatus is large. However, because the electric motor requires so much space, the damping space of the sound absorber must be small.
Because of the nested structure of the electric motor and the sound absorber, it is hardly possible to adjust an electro-pneumatic performance of the electric air-pump apparatus for possible changed requirements because an installation space for the electric motor is limited.
German patent document (DE 42 39 575 C2,) discloses an additional electric air-pump apparatus for motor vehicles, whose sound absorber is positioned on a side of a mounting plate facing away from an electric motor. This sound absorber, however, independently of the electric motor, mounting plate, and pumping device, is arranged as a separate component, which can be snapped subsequently onto a housing of the pumping device. A disadvantage of this solution is that the sound absorber is structured in a costly manner as a separate component.
It is an object of the invention to provide an electric air-pump apparatus for motor vehicles having an uncomplicated and inexpensive structure that requires little installation room.
According to principles of this invention, a sound-absorber cap of an electric air-pump apparatus surrounds a pumping. device and the sound-absorber cap is placed on a side of a mounting plate facing away from an electric motor.
By arranging the sound-absorber cap in the manner of this invention, an outer diameter of an electric air-pump apparatus of the invention can be significantly reduced. Additionally, one electric motor can easily be replaced by another motor having different outside dimensions, without requiring changes to the sound-absorber cap for that purpose.
Because in this invention the sound-absorber cap surrounds the pumping device, no prearranging of leads or chambers between the pumping device and the sound-absorber cap is necessary for creating the sound absorber. This measure also ultimately saves on installation space, and results in a damping space of the sound absorber being large in comparison to those of the prior art, even though outer dimensions of the sound-absorber cap are small. This leads to very effective sound absorption of intake and exhaust noises.
The solution of the invention ultimately can be achieved with less complicated and less costly measures relative to the prior art, because the sound absorber is formed solely by the mounting plate and the sound-absorber cap structured in a very uncomplicated shape, which does not require any sort of internal chambers or channels. The electric air-pump apparatus according to the invention can be installed with very uncomplicated measures because the sound-absorber cap is simply placed over the pumping device, after the pumping device is mounted on the mounting plate, and fastened to the mounting plate.
Advantageous embodiments and further developments of the invention are also possible.
Thus the electric air-pump apparatus can advantageously include a suction pumping device, with which a vacuum is generated. Particularly in this case, the mounting plate can have an intake column and/or an outlet channel for the conveyed air, so that the sound-absorber cap does not need to have any holes or tube-like connecting parts for creating such channels.
In this connection, the mounting plate can have a recess in an area of the outlet channel, which in conjunction with a flange edge of the sound-absorber cap, forms a labyrinth for preventing moisture, for example in the form of water spray, from entering into the damping space of the sound absorber in an unwanted manner. In order to remove condensation water from the damping space, particularly if condensation forms in the damping space of the sound absorber, it is especially advantageous for the outlet channel to be positioned below the pumping device and thereby open into the sound absorber at the lowest point of the sound absorber.
As an additional functional characteristic. the mounting plate can, in a particularly advantageous manner, have a fastening flange that makes it possible to attach the entire electric air-pump apparatus to a support. In this way, suitable fastening parts are not required in the area of the sound-absorber cap. Similarly, in a particularly advantageous manner, the mounting plate has a seat for a motor shaft bearing and/or a seat for a brush holder of the electric motor, in order to assume some functions of the motor housing of the electric motor. This simplifies construction of the remainder of the electric motor, and also results in a reduction of costs and expense of construction of the electric air-pump apparatus of this invention.
In a particularly advantageous manner, the mounting plate can be die-cast of metal, particularly aluminum, whereby, in an especially advantageous manner, the functional parts described above, the intake column, outlet channel, recess, mounting plate, and seats for the motor shaft bearing and brush holder, can be formed as a single part with the mounting plate. This also contributes to simplification of the electric air-pump apparatus and, thus, to a reduction in manufacturing costs.
Finally, in a particularly advantageous manner, the pumping device may be a vane-type pumping device, with the individual pump parts, base plate, rotor, ring, and cover, being made in a known manner of a carbon-plastic compound, which has the particular advantage of high abrasion resistance and low friction. The functional parts of the pumping device, then, are structured independently from the mounting plate so that a service life of the pumping device can be increased significantly over those of pumping devices of such electric air-pump apparatus in the prior art.